1. Field of Invention
The present invention relates to a filament winding apparatus for winding a plurality of filamentary yarns impregnated with a resin onto a plurality of mandrels, respectively, and more particularly to a filament winding apparatus which can exchange from a plurality of full mandrels at once or in one lot easily and efficiently into a plurality of empty mandrels.
2. Description of the Prior Art
In a conventional filament winding apparatus for producing fiber reinforced plastics (FRP), it takes much time and many hands for exchange of mandrels because of many operations to remove and set many mandrels individually from and onto the apparatus. Namely, after filamentary yarns impregnated with a resin are wound onto mandrels, firstly, by hands or by using a mandrel donning and doffing apparatus, the mandrels are detached from winding shafts of a winder and transferred to a mandrel storage stand. Then, empty mandrels prepared on another stand are transferred to the winder, and attached to the winding shafts. In the exchange of mandrels in a filament winding apparatus of which winder has multiple winding shafts, the above operation must be conducted successively one by one. Even if a mandrel donning and doffing apparatus is used, the distance between the adjacent winding shafts of the winder must be designed sufficiently large so that troubles do not occur when the parts of the mandrel donning and doffing apparatus are inserted therebetween. Therefore, the number of the winding shafts incorporated into a single winder is limited to two or three although the limited number varies depending on the shape of the products to be formed. In such a limited condition, sufficient advantage due to a multiple winding cannot be obtained.
Moreover, dollies are frequently used for the operation of conveying empty mandrels to a mandrel storage stand of a filament winding apparatus and the operation of the conveying mandrels wound with filamentary yarn, that is, full mandrels, from another stand to a next process. In these operations, in practice, the mandrels are transferred one by one between the dollies and the stands by hands or by using mandrel exchange apparatuses, and it is inefficient.
An automated system wherein a plurality of mandrels are automatically conveyed between a mandrel preparing apparatus, a filament winding apparatus, a curing furnace, a post-processing apparatus, a mandrel removing apparatus, etc., and the respective operations are performed during the conveying, is disclosed in U.S. Pat. No. 4,671,842. In this system, however, there are some problems such as ones that it is difficult to harmonize the treatment times of the respective apparatuses in the system and that the system becomes to be a large scale and requires a great cost and a quick response cannot be made.
On the other hand, the conventional filament winding apparatus itself has some problems. For example, after formation of full mandrels, in the operation of changing filamentary yarns from full mandrels to empty mandrels, each filamentary yarn connected to each of the full mandrels is cut and the cut end of the filamentary yarn is held on a part of the apparatus, and after exchanging mandrels for the full mandrels to empty mandrels, each held filamentary yarn is wound by hand onto each empty mandrel for preparing a next winding session. On this step, it takes much time and many hands for such a filamentary yarn changing operation.
Furthermore, usually a tape is wound on the outer surface of a layer formed on the mandrel comprising the filamentary yarn impregnated with resin wound thereon, for squeezing air from the layer mixed therein in form of bubbles. The tape is usually rewound from a reel attached to the filament winding apparatus. A part of or the whole of this tape winding operation is also performed by hand. Therefore, the tape end must be pulled out from the reel by hand, and after the tape is wound, the tape must be cut manually and the tape end retained on the mandrel side is fixed on the surface of the layer by an adhesive tape. On this operation, also it takes much time and many hands.